In general, door assemblies contain a number of components including a frame, a door configured to fully or partially fill the aperture created by the frame, a hinging mechanism to both retain the door within the frame and facilitate movement of the door relative to the frame, and a closure mechanism for retaining the door in the closed position within the frame. Depending on the function and type of door these components can vary. For example, a cupboard door may be attached directly to the side panels of a cabinet and not require a separate frame member.
As aforesaid, a closing mechanism mounted in the door retains the door in its closed position and prevents the door from opening unexpectedly. One commonly used closure mechanism is a latch retained within a housing and operatively connected to a handle. The housing is inset into the side edge of a door and the latch is biased by a spring into a position whereby it extends from the housing. Rotational movement of the handle causes the latch to retract against the spring into the housing. As the latch is biased by the spring, releasing the handle causes the latch to revert to its extended position. The frame of the door is fitted with a recess adapted to receive the latch. Thus, when the door is closed, the latch is retained in the recess by the biasing spring, preventing the door from opening until the latch is retracted via the handle.
Such closure mechanisms can be used in combination with a lock to prevent opening of the door. For example, a closure mechanism in the form of a spring operated latch as previously described may be coupled with a separate dead bolt. Sliding the dead bolt into the frame will prevent the door from opening even if the spring operated latch is disengaged. More often the lock will be coupled directly to, or form a part of, the closure mechanism such that enabling the lock restricts operation of the closure mechanism. For example, a closure mechanism in the form of a spring operated latch as previously described may be coupled with a means for restricting movement of the handle.
One disadvantage of common closing mechanisms is the large number of moving parts in the mechanism which may fail after continued use. In the event of a failure of the handle for example, if the door is closed the latch will be biased toward the recess in the door frame and there may be no easy means for retracting it so as to open the door without damaging the door, the latch and/or the door frame.
In order to reduce the large number of moving parts associated with closing mechanisms which can fail due to wear and tear, locking devices using magnets for closing doors are also known, some of which are disclosed in the following publications:
U.S. Pat. No. 3,600,025 discloses a releasable magnetic latch especially suitable for cabinet doors and the like having a spring means to be biased upon manual engagement and urging of the cabinet door inwardly from its normal closed position and to urge the door outwardly into an open position and past the range of the magnetic latching effect when the door is suddenly released from said manual engagement.
U.S. Pat. No. 3,934,909 discloses a push releasable magnetic latch for cupboard doors or the like, comprising a first magnetic member secured to the cupboard door and a second magnetic member swing mounted to the cupboard structure about a pivot axis perpendicular to the path of travel of the door. The second member has a forward latching position and a rearward non-latching position, with a spring pushing the second member to its forward latching position. To open the door, the door is pushed inwardly to force the second magnetic member to its non-latching position where the two magnetic members are out of engagement, after which the door is abruptly released so that the spring causes the second member to push the door outwardly away from the cupboard structure.
As the magnetic catches discussed above (and other types of magnetic/spring etc catches known in the prior art) have components that are surface mounted onto the door and door frame/jamb i.e. not hidden when the door is closed, there are many instances where these types of catches are not a suitable fitting. For example, double doors into a lounge area, or a single door into a room where the main components of the catch (normally a plastic rectangular shape box or a metal unit) is exposed and is considered too unsightly when viewed from inside the room.
Other types of prior art devices include concealed spring loaded roller and ball catches. However, these types of catches tend to be labour intensive to install, and as aforementioned have moving parts that wear out and require adjustment over time and are considered noisy during operation.
While there are prior art devices capable of performing the push releasable latching function as described above, there are continuing efforts to devise improved magnetic latching assemblies. From the above, it appears that the current magnetic latch technology is simple enough and easy to install in theory, but in practice a few problems present themselves.
For example, it can be difficult to drill holes for installation of a magnetic latching assembly in a neat and tidy fashion as to give sufficient holding power large magnets must be used and the holes for locating and housing the magnets must be similarly large. Furthermore, the wood types used for internal joinery are normally soft (in New Zealand, pine is mainly used) which often results in an oval hole with chips around the edges rather than a round hole. This leads to a poor quality finish which is visible when the door is open. This is not typically a problem for other kinds of closure mechanisms as they will usually have a plate or flange that covers the hole that is recessed into the wood.
It also can be difficult to precisely align and drill holes to align magnets as the installer is often drilling overhead or on top of a ladder which results in a substandard finish and fitting. In some instances, such as the installation of heavy double glass hallway doors, the magnets need to be installed with minimal distance between them for maximum attraction and power. If the magnets are not parallel to each other, a minimal distance can not be achieved as described further below.
A specific type of magnetic closure system involves flush mounting the magnets with respect to the surface of a door jamb and the top of a door. This mounting configuration of the magnets is desirable for aesthetic appeal.
However, it can be difficult to install the magnets with a minimum exposure or optimum depth (i.e. flush mounted) in some situations for example when installing magnets on double doors. In double door applications the size of the gap between the door and the frame of one door may differ from that of the other which would result in a different attractive force between the magnets on the respective doors if both were flush mounted. This would manifest itself in one door being easier (or harder) to open relative to the other. Also, if the closure mechanism of one of the doors is weaker, the weaker door may open when the other door is shut due to the air pressure effect inside a cupboard, room or the like.
Therefore, it is an object of the present invention to provide a magnetic closure assembly which is inexpensive to manufacture, easy to install and capable of adjustment and which addresses the foregoing problems or at least provides the public with a useful choice.
All references, including any patents or patent applications cited in this specification are hereby incorporated by reference. No admission is made that any reference constitutes prior art. The discussion of the references states what their authors assert, and the applicants reserve the right to challenge the accuracy and pertinency of the cited documents. It will be clearly understood that, although prior art publications are referred to herein, this reference does not constitute an admission that any of these documents form part of the common general knowledge in the art, in New Zealand or in any other country.
It is acknowledged that the term ‘comprise’ or grammatical variations thereof may, under varying jurisdictions, be attributed with either an exclusive or an inclusive meaning. For the purpose of this specification, and unless otherwise noted, the term ‘comprise’ shall have an inclusive meaning—i.e. that it will be taken to mean an inclusion of not only the listed components it directly references, but also other non-specified components or elements. This rationale will also be used when the term ‘comprised’ or ‘comprising’ is used in relation to one or more steps in a method or process.
Further aspects and advantages of the present invention will become apparent from the ensuing description which is given by way of example only.